Hydroxyphenylalkyleneyl isocyanurate/thiophosphite combinations as stabilizers for organic materials

ABSTRACT

Organic materials subject to thermal and/or oxidative degradation are efficiently stabilized using a combination of a hydroxyphenylalkyleneyl isocyanurate compound and a thiophosphite compound. The stabilized compositions exhibit exceptional stability, better than that achieved using either compound alone or using any known combination of phenolic and phosphorouscontaining stabilizer compounds.

United States Patent Gilles Sept. 30, 1975 HYDROXYPHENYLALKYLENEYL 3,496,128 2/1970 Casey et al. 260/23 ISOCYANURATE/THIOPHOSPHITE 3,637,582 1/1972 Gilles 260/45.8 3,666,837 5/1972 Rattenbury 260/928 COMBINATIONS AS STABILIZERS FOR ORGANIC MATERIALS [75] Inventor: Jack C. Gilles, Shaker Heights, Ohio [73] Assignee: The B. F. Goodrich Company, Akron, Ohio [22] Filed: Oct. 15, 1973 [21] Appl. No.: 406,344

[52] US. Cl...... 260/45.8 NT; 252/400 A; 252/404; 260/45.7 PS; 260/45.8 R; 260/398.5 [51} Int. Cl. C08K 5/34; COSK 5/49 [58] Field of Search. 260/45.7 PS, 45.8 NT, 45.8 R; 252/400 A [56] References Cited UNITED STATES PATENTS 3,359,234 12/1967 Milionis et a1, 260/45.75

Primary E.raminerDonald E. Czaja Assistant ExaminerR. A. W hite Attorney, Agent, or Firm-Alan A. Csontos [57] ABSTRACT Organic materials subject to thermal and/or oxidative degradation are efficiently stabilized using a combination-of a hydroxyphenylalkyleneyl isocyanurate compound and a thiophosphite compound. The stabilized compositions exhibit exceptional stability, better than that achieved using either compound alone or using any known combination of phenolic and phosphorouscontaining stabilizer compounds.

10 Claims, N0 Drawings HYDROXYPHENYLALKYLENEYL Y Y y. ISOCYANURATE/THIOPHOSPHITE R3S\" "/SR3 COMBINATIONS AS STABILIZERS FOR ORGANIC ,P-s-+ RS-P-S-hRS-P MATERIALS 12 s I BACKGROUND OF THE INVENTION Phenolic compounds, particularly hydroxyphenyl substituted heterocyclic compounds, are known to be stabilizers for organic materials. Phosphoruscontaining compounds, particularly phosphates and 1() phosphites, are also known to be stabilizers for organic materials. Specific combinations of phenolic compounds and phosphorous-containing compounds are also disclosed in the art. Relevant art in this area is: US. Pat. Nos. 3,112,272; 3,115,466; 3,145,176; 15 3,294,736; 3,333,027; 3,531,483; 3,567,724; 3,652,561; 3,666,837, and 3,678,047.

SUMMARY OF THE INVENTION Combinations of 1 a hydroxyphenylalkyleneyl iso- 20 cyanurate of the formula wherein n is to 9; R is an alkylene radical of l to about 20 carbon atoms, an alkyloxyalkyl or a1kylthioalkyl radical containing 2 to about 20 carbon atoms, a cycloalkylene radical of to 6 carbon atoms in the ring, or an arylene radical of 6 to 10 carbon atoms; R, is an alkyl radical of 1 to about carbon atoms; and Y is nothing or oxygen, are useful as stabilizers for organic materials. Stabilized compositions containing the combination exhibit exceptional thermal and/or oxidative stability.

DETAILED DESCRIPTION OF THE INVENTION The combination of a hydroxyphenylalkyleney] isocyanurate compound and a thiophosphite compound is an exceptionally good thermal and/or oxidative stabilizer for organic materials. The hydroxyphenylalkyleneyl isocyanurate compound is used at a level from 8 about 0.01 part to about 5 parts by weight, and more preferredly at from about 0.05 part to about 3 parts by RI I r I weight per 100 parts by weight of the organic material. a I v The thiophosphite compound is employed at similar 0:0 7 (1:0 levels, i.e., from about 0.01 part to 5 parts and prefera- N bly at about 005 part to about 3 parts by weight per 100 parts by weight of organic material. Thus, the com R" bined weight of the compounds is from about 0.02 part to about 10 parts and more preferredly from about 0.1

' to 6 parts by weight per 100 parts by weight of organic wherein is hydroxyphenylalkylcneyl radlcal of the material. The hydroxyphenylalkyleneyl isocyanurate formula can be used in from about a 10:1 to 1:10 weight ratio of isocyanurate compound to thiophosphite compound. Excellent results are obtained at about a 3:1 to

r r 1:3 weight ratio. A 1:1 weight ratio of the compounds 40 provides very effective stabilization of organic materials. m ZITL 0 The hydroxyphenylalkyleneyl isocyanurate compounds have the formula III --.r r -where m is 1 to 4, r is an alkyl radical having 1 to 18 R D carbon atoms and is positioned immediately adjacent O-u -0 to the hydroxyl group on the ring; r 1' and r., are by drogen or an alkyl radical containing 1 to 18 carbon atoms; and R" and R' are hydrogen, an alkyl radical R" containing 1 to 18 carbon atoms, or are the same as R; and (2) a thiophosphite compound selected from the whereinRisahdox he l'-lkl l'd"l ft group consisting of(a) an alkylthiophosphite ofthe fory r yp ny d y eney m led 0 he formula mula:

2 l H l R23 m r 0?:

wherein R, is an alkyl radical containing about 8 to 31 about 20 carbon atoms and R is the same as R or both 2 radicals fOTm with thiophosphorousthio where m is 1 to 4, r is an alkyl radical having 1 to 18 structure a cyclic ring of 5 to about 8 atom and carbon atoms and is positioned immediately adjacent a polya ky thiopo yp osphi 0f the formula to the hydroxy group on the ring; r r;, and r are hydrotert-alkyl-4-hydroxybenzyl)isocyanurates of the for mula CH2- -OH where n is 4 to 8. I A

Examples of the 4-hydroiiybenzyl isocyanurate com pounds are: tris-(3-methyl-4-hydroxybenzyl)isocyanurate, tris-( 3-t-butyl 4-hydroxybenzyl )isocyanurate, tris- (3-t amyl-4-hydroxybenzyl)isocyanurate, tris-(3- cetyl- 4-hydroxybenzyl)isocyanurate, tris-(3,5-dimethyl-4- hydroxybenzyl)isocyanurate, tris-(3,5-diisopropyl-4- hydroxybenzyl)isocyanurate, t ris-( 3-methyl-5- isopropyl-4-hydroxybenzyl )isocyanuratc, tris-( 3- cyclohexyl-4-hydroxybcnzyl(isocyanuratc, tris-(3,5-di t-butyl-4-hydroxybenzyl)isocyanurate, tris-(3-t-butyl- -t-arnyl-4-hydroxybenzyl)isocyanurate, tris-(3,5-di-tamyl-4-hydroxybenzyl )isocyanurate, tris-[ 3,5-di-( lmethyl-1-ethylpropyl)4-hydroxybenzyllisocyanurate, tris-l 3 ,5-di-( l l ,2,2-tetramethylpropyl)-4-hydroxybenzyl]isocyanuratc, tris-[3,5-di-( l-dimethylpentyl)-4- hydroxybenzyl]isocyanuratc, bis-(3-methyl-4-hydroxybenzyl )-isocyanurate, bis-( 3-t-butyl-4-hydroxybenzyl- )isocyanurate, bis( 3 ,5-dimethyl-4-hydroxybenzyl- )isocyanurate, bis-(.3,5-di-t-butyl-4-hydroxybenzyl- )isocyanurate, (3-methyl-4-hydroxybenzyl)isocyanurate, (3-t-butyl-4-hydroxybenzyl)isocyanurate, (3,5- dimethyl-4-hydroxybenzyl)isocyanurate, (3,5-di-tbutyl-4-hydroxybenzyl)isocyanurate, and the like. Reference is'made to US. Pat. No. 3,531,483 which discloses isocyanurate compounds encompassed by this invention. The patent shows the preparation of these compounds and their utility as stabilizers, and is hereby incorporated by reference.

The thiophosphite compound is selected from the group consisting of alkylthiophosphites and polyalkylthiopolyphosphites. The alkylthiophosphites have the formula wherein R is an alkyliiradical containing about 8 to about 20c arbon atorns andjl l is the same as R or both R radicals form with the" thiophosphorousthio structure a cyclic ring of 5 to about 8 atoms.

Examples of the alkylthiophosphite are tris(octylthio) phosphite', tris( Z-ethylhe'xylthio)phosphite, tris(decylthio)phosphite, Itris(dodecylthio)phosphite, tris( tetradecylthio )phosphite, tris( octadecylthio phosphite, mono( dodecylt hio)bis(octadecylthio)- phosphite, mono(octylthio )ethylenedithio phosphite, and the like More preferredly, R and R are alkyl radicals as defined above.

The polyalkylthiopolyphosphite compounds have the formula wherein n 0 to 9; Risan alkylene radical of l to about 20 carbon atoms, an alkyloxyalkyl or alkylthioalkyl radical containingZ to about 20 carbon atoms, a cycloalkylene radical of 5 to 6 carbon atoms in the ring, or an arylene radical of 6 to 10 carbon atoms; R; is an alkyl radical of l to about 20 carbon atoms in the radical, and Y is nothing or oxygen. More preferredly, n O and R is either an alkylene radical of l to about 10 carbon atoms or an alkylox'yalkyl radical containing 2 to about l0'carbon atoms, and Y is nothing.

Examples of the polyalkylthiopolyphosphite compounds are: tetrakis(ethylthio)1,2-dithioethylene diphosphite, tetrakis(hexylthio)l,2-dithioethylene diphosphite, tetrakis(dodecylthio)1,2-dithioethylene diphosphite, tetrakis(butylt hio)l,2-dithiopropylene diphosphite, tetrakis( isopropylthio) l ,3-dithiopropylene diphosphite, tetrakis(methylthio)1,6-dithiohexylene diphosphite, di(ethylthio)di(propylthio) l ,6- dithiohexylene diphosphite, tetrakis(t-butylthio)1,6- dithiohexylene diphosphite, tetrakis(sec-butylthio)1,6- dithiohexylene diphosphite, tetrakis(2-ethylhexylthid) l ,-dithiohexylene diphosphite, tetrakis(dodecylthio) l ,6-dithiohexylene diphosphite, tetrakis(hexadecylthi0) l ,6-dithiohexylene diphosphite, tetrakis(octadecylthio)1 ,6-dithiohexylene diphosphite, tetakis(eicosanylthio) l ,6-dithiohexylene diphosphite, tetrakis(decylthio)l ,20-dithioeicosanylcnefdiphosphite, tetrakis(dodecylthio)B,B-dithioethylether' diphosphite, tetrakis(- late,

dodecylthio)om ega, omega dithiooctylether diphosphite, tetrakis(dodecylthio)p-dithiophenylene diphosphite, tetrakis(dodecylthio)2-methyl l ,4-dithiophenylene diphosphite, tetrakis(cetylthio)dithioeyclohexylene diphosphite, tetrakis(dodecylthio) l ,4-bis(thiomethyl benzene diphosphite, tetrakis( dodecylthio) l ,4 bis(thiomethyl)cyclohexane diphosphite, tetrakis(dodecylthio) l ,3dithiocyclopentylene diphosphite, tetrakis (dodecylthio) l ,8-dithionaphthalene diphosphite, pen takis(dodecylthio )bis( 1,6-hexylenedithio )triphosphite, pentakis(octadecylthio)bis( l ,2-ethylenedithio)triphosphite, pentakis(isodecylthio)bis(flfi -dithioethyletherJtriphosph'ite, hexakis( dodecylthio)tris( 1,6- hexylenedithio)tetraphosphite, heptakis(dodecylthio)- tetrakis( 1,6-hexylenedithio)pentaphosphite, and dode cakis(dodecylthio)nonakis( l,6-hexylenedithio)decaphosphite. Reference is made to u.S. Pat. No. 3,666,837 which discloses thiophosphite compounds encompassed by this invention. The patent shows the preparation of these compounds and their utility as stabilizers, and is hereby incorporated by reference.

The combination of the isocyanurate compound and the thiophosphite compound as defined herein provides exceptional thermal and/or oxidative stability to organic materials. Stabilized composition containing the combination exhibit better stability then compositions containing either compound alone, or compositions containing known combinations of a phenolic stabilizer and a phosphorous-containing stabilizer.

Organic materials which are stabilized in accordance with the presence invention include both natural and synthetic polymers. The combination is useful for the stabilization of ceilulosic materials; natural rubber; halogenated rubber; homopolymers of ethylene, propylene, butene-l, isobutylene, pentene-l, hexene-l, 4-methyl-l-pentcne, and the like, or copolymers thereof such as ethylene-propylene copolymer, ethylene-butene-l copolymer, 4-methyl-l-pentene-hcxenel copolymer, and the like; ethylene-propylene-diene rubbers wherein the diene is 1,4-hexadiene, 2-methyl- 1,4-hexadiene, a dimethyl-l,4,9-decatriene, dicyclopentadiene,vinyl cyclohexene, vinyl norbornene, ethylidene norbornene, methylene norborene, norbornadiene, methyl norbornadienc, methyl tctrahydroindene, and the like; conjugated diene polymers, as, for instance, polybutadiene, copolymers of butadiene with styrene, acrylonitrile, acrylic acid, alkyl acrylates or methacrylates, methyl vinyl ketone, vinyl pyridine, etc., polyisoprene, polychloroprene, and the like; vinyl polymers such as polyvinyl chloride, polyvinyl fluoride, polyvinylidene chloride, copolymers of vinyl chloride with vinylidene chloride, polyvinyl acetate, copolymers of vinyl halide with butadiene, styrene, vinyl esters, a,/3-unsaturated acids and esters thereof, a,Bunsaturated ketones and aldehydes, and the like; homopolymers and copolymers of acrylic monomers such as acrylic acid, methylacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, 3-ethylhexyl acryacrylamide, methacrylamide, N- methylolacrylamide, acrylonitrile, methacrylonitrile, and the like; polyetheror polyol-derived polyurethanes; acetal homopolymers and copolymers; polycar bonates; polyesters such as those derived from maleic, fumaric, itaconic, or terephthalic anhydrides, or the like; for example, polyethylene terephthalate; polyamides such as those derived from the reaction of hexamethylenediamine with adipic or sebacic acid; epoxy resins such those obtained from the condensation of epichlorohydrin with bisphenols; and the like. Polymer blends, thatis, physical admixture of two or more poly mers-may also be stabilized in accordance with the present invention.

in addition to polymeric materials, the present compounds act to stabilize a wide variety of other organic materials. Such compounds include: waxes, synthetic and petroleum-derived lubricating oils and greases; animal oils such as, f0r example, fat, tallow, lard, cod-liver coil, sperm ,oil; vegetable oils such as castor, linseed, peanut, palm, cotton seed, and, the like; fuel, oil; diesel oil, gasoline, and the like.

- The novel combination of this invention is especially useful for the stabilization of a-monoolefin homopolymers and copolymers, wherein the a-monoolefin contains 2 to about 8 carbon atoms. Highand low-density polyethylene, polypropylene, polyisobutylene, poly( 4-methyl-l-pentene) have excellent resistance to oxidative attack when stabilized with the combinations of the present invention. Ethylene-propylene copolymers and ethylene-propylene terpolymers generally containing less than about 10% by weight of one or more monomers containing multiple unsaturation also are stabilized using the combination.

The compounds are readily incorporated into the organic materials by dissolving or dispersing them within the materials. If the material is a solid, especially a polymeric solid such as a rubber or a plastic, the compounds can be admixed using Banburys, extruders, tworoll mills, and the like, following conventional techniques. A good way to disperse the compounds in plastic materials is to dissolve or suspend the compounds in a solvent such as acetone or benzene, mix the mixture with the plastic in powder form, and then evap orate off the solvent.

Compositions containing the novel combination of compounds can also contain many other known compounding ingredients such as fillers like carbon black, silica, metal carbonates, talc, asbestos, and the like; pigments and colorants; curative ingredients like sulfur and peroxides and vulcanization accelerators; fungicides and many more standard ingredients known to the art.

The novel combination ofa hydroxyphenylalkyleneyl isocyanurate compound and a phosphite compound was evaluated as a stabilizer for a polymeric a-monoolefin homopolymer. Testing consisted of both thermal and oxidative stability of prepared samples. In addition to the novel combinations of this invention, other phenolic compound/phosphorous-containing compound stabilizer comcbinations were evaluated. All samples were prepared by dissolving the stabilizer compounds in benzene, swelling the polypropylene polymer in benzene, admixing the two mixes, and evaporating off the benzene. The stabilized composition is then extruded at 220C, at 50 rpm and test samples molded from the extrudate at 220C. to form strips 1 inch by 2 inches by 30 mils thick. These strip samples are employed in the oven aging and oxygen absorption tests.

The thermal stability (oven aging) testing consisted of aging of samples in an air-circulation oven at C.

until visual cracking of the sample was observed. At the first signs of crack development, the strip is bent slightly to see if it breaks (embrittlement). The time to the onset of cracking or embrittlement is measured. Samples are run in duplicate and the data averaged.

The oxidative stability (oxygen absorption) test consisting of aging the samples at 150C. in an atmopshere of pure oxygen and recording the oxygen uptake of the samples. The test used in a standard oxygen absorption The data shows that excellent stability is provided over a broad weight ratio and broad levels of the defined compounds. At higher levels of use, samples 6, 7 and 8, exceptionally good thermal and oxidative stability is test where the samples are hung in pure oxygen and the obtained. volume of oxygen in the chamber measured. At a decrease of 0.1 cc of oxygen in the chamber (taken up by the sample), 0.1'cc of oxygen is added to the chamber EXAMPLE m and its addition recorded. The measurement is then oxd mand u 'ke in the chamber versus time. e pm 10 Sample compositions Were prepared using different This data is plotted and time to failure 1s determined by phenolic stabihzers 1n comblnatlon with the polyalkyl-- the onset of rapid oxygen uptake by the sample. Test l d t a d the d t v d thiopolyphosphite compound employed In Example II. ra? fi t m upllca e 3 3 f The samples were prepared using 0.1 part by weight h f f exanp es t l usfra 8 each of the phenolic stabilizer and the tetrakis(dodecyt e matlons. an .composmons lthio)-l,-dithiohexylene diphosphite per 100 parts by The reclpes are given in parts by weight unless other- S ecified weight of propylene (a 1:1 weight ratio of phenohc to wlse p thiophosphite). Tests were run to determine thermal stability of the compositions. EXAMPLE I Compositions were prepared containing polypropylene and a hydroxyphenylalkyleneyl isocyanurate and /or a polyalkylthiopolyphosphite compound as defined 140C. in this invention. The sample compositions were tested Oven Agmg Phenolic Compound Hours for the1r thermal and oxidative stability. Recipes and data obtained are as follows: Tetrakis(methy1ene-3-(3,5'-di-t-butyl- 2580 4hydroxyphenyl )propionate )methane Bis( 3,5di-t-butyl-4-hydroxybenzyl )-di- 2376 dodecyl malonate 2.2',2"-tris( 3- 3.5-di-t-buty1-4- 2376 1 2 3 4 5 6 hydroxyphenyl)propionyloxy)ethylisocyanurate Polypropylene" 100 100 100 1()() 100 100 2,4 -i (3 5.di t-b t l 4-h d 1716 lsocyanurate compound" 0.25 0.50 0.25 benzylthionriazine ThlOphOSphitE COmPOUHd" 0.25 0.50 0.25 l 3 5(3 5-di-t-butyl-4 hydroxybenzyl) 3480 isocyanurate 140C. oven test, less 250 710 168 360 8536 hours than 24 hrs.

150C. oxygen less 8 12.5 2 22 414 flbsmnlmn The data shows the superior results obtained when emtest, hours 1 hr.

40 ploymg the hydroxyphenylalkyleneyl 1socyanurate "General purpose resin (Profax 6501) compound of this invention (sample 5 versus samples "1. -lris(3.5-di-t-hutyl-4-hydroxybenzyl)isocyanuratc l to "te s(dodcc vlthi0)-l.6-dithiohexylene diphosphitc The data shows that sample 6, using a combination of EXAMPLE IV this invention, provides far superior stability to polypropylene than the use of either compound alone. The hydroxyphenylalkyleneyl isocyanurate compound employed in Example 11 was used in combina- EXAMPLE 11 tion with different phosphorous-containing stabilizers to prepare sample compositions. The 1,3,5-tris(3,5-di- A series of samples were prepared at various weight t-butyl-4-hydroxybenzy1)isocyanurate and phosphorratios of hydroxyphenylalkyleneyl isocyanurate comous-containing compounds were used at a 1:1 weight pound to polyalkylthiopolyphosphite compound. The ratio, both compounds used at 0.25 part by weight per recipes and evaluation data obtained are given in the 100 parts by weight of propylene. The recipes used and following table. data obtained follow.

Polypropylene 100 100 100 100 100 100 100 l,3,5-tris(3,5-di-t-buty1-4- 0.1 0.1 0.15 0.25 0.25 0.25 0.25 0.10

hydroxybenzyl )isocyunuratc Tctrakis(thiododecyl)-1,o-di- 0.05 0.1 0.1 0.05 0.1 0.25 0.50 1.0

thiohcxylcnc diphosphite Weight ratio 2:1 1:1 1.5:1 5:1 25:1 1:] 1:2 1:10

C. oven aging, hours 744 3480 3816 3444 6000 8536 8832 6264 C. oxygen absorption, hours 7.2 12.5 14.0 30.4 82 414 865 326 140C. l 50C.

Oven Aging Oxygen Sample Phosphorous-Containing Compound Hours Absorption l Tris(nonylphenyl)phosphite 3072 30 2 Triphenyl phosphite 3780 19 3 Tris(p-methoxyphenyl)phosphite 4824 l8 4 Tris(p-phcnyl phenyl)phosphite 2412 I CEIHHD OCH2 CH-ZO 6 C ,,,H,,,0 P C P 0C,,,H,,, 3744 I OCH (SH- O 7 di(dodecyloxy)hydrogen phosphate 4656 26 8 Tris(dodccylthio)phosphitc 3720 l 12 9 Tetrakis(dodecylthio)-l,-dithiohexylcnc diphosphite 8536 414 The data shows the far superior oxidative stability drogen or an alkyl radical containing 1 to 18 carbon (150C oxygen absorption) of compositions containatoms; and R" and R are hydrogen, an alkyl radical ing the stabilizer combination of this invention (samcontaining 1 to 18 carbon atoms, or are the same as R, ples 8 and 9 versus samples 1 to 7). Sample 9, containand (2) a polyalkylthiopolyphosphite of the formula ing the polyalkylthiopolyphosphite compound, has oxidative and thermal stability far superior to any known B S SP phenolic/phosphorous-containing compound combina- 3O 3 S P 3 tion. The stabilization achieved is totally unique and R S n SR3 unexpected. J SR I claim:

1. As a stabilizer for organic materials subject to oxidative and/0r thermal degradation, a combination consisting essentially of l a hydroxyphenylalkyleneyl isocyanurate of the formula wherein n O to 9; R is selected from the group con sisting of an alkylene radical of 1 to about 20 carbon atoms, an alkoxyalkyl or alkylthioalkyl radical containing 2 to about 20 carbon atoms, a cycloalkylene radical of 5 to 6 carbon atoms in the ring, and an arylene radi- 9 40 cal of 6 to 10 carbon atoms; R is an alkyl radical of l to about 20 carbon atoms; said hydroxyphenylalkylen- R eyl isocyanurate compound used in a weight ratio of i I about 10:1 to 1:10 to the thiophosphite compound.

o=c C=O 2. A combination of claim 1 where in l R" and R are equal to R, r is a tertiary alkyl radical containing I 4 to about 12 carbon atoms, r is an alkyl radical con- R" taining l to about 12 carbon atoms, r and r, are hydrogen, and m =1.

wherein R is hydroxyphenylalkyleneyl radical of the A Combmanon of clalm 2 where (I) has the for- I OH where m is l to 4, r, is an alkyl radical having 1 to 18 where n is 4 to 8. carbon atoms and is positioned immediately adjacent 4. A combination of claim 3 where in (2), n O, and to the hydroxyl group on the ring; r r and r., are hy- R is an alkylene radical of l to about 10 carbon atoms or an alkoxyalkyl radical containing 2 to about ll) carbon atoms.

5. A combination of claim 4 consisting of 1,3,5- tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate and tetrakis(dodecylthio)-1,6-dithiohexylene diphosphitc. 5

6. A composition comprising (A) an organic material subject to oxidative and/or thermal degradation, and (B) as the only stabilizer, a combination of (l) a hydroxyphenylalkylcneyl isocyanurate of the formula wherein R is a hyd'roxyphenylalkylencyl radical of the formula v Whercinn =0 to 9; R is selected from the group consisting of an alkylene radical of l toabout 20 carbon atoms, an alkoxyalkyl or alkylthioalkyl radical containing 2 to about 20 carbon atoms, a cycloalkylene radical of 5 to 6 carbon atoms in the ring, and an arylene radical of 6 to, lQcarbon atoms; R, is an alkyl radical of l to about 20 carbon atoms; said hydroxyphcnylalkyleneyl isocyanurate compound used at a level of from about 0.0l part to about 5 parts by weight per parts by weight of organic material. said thiophosphite compound used at a level of from about 0.01 part to about 5 parts by weight per iOO parts by weight of organic material, and said hydroxyphenylalkyleneyl isocyanurate compound used in about a 10:1 to 1;l 0 weight 7 ratio to the thiophosphi tc compound.

7. A compositionof claim 6 wherein (A is a polyamonoolefin polymer, and in (B) (,1), R and R are the same as ,R, r is a tertiary alkyl radical containing 4 to about l2 carbon atoms, r is analkyl radical containing l to about 12 carbon atoms, r and r are hydrogen, andm =,,l. H I

8. A composition ofclaim 7 wherein (A) is a polyamonoolefin homopolymer and in (B) (2), n O, and R is an all tylene radicalof l to about 10 carbon atoms or 

1. As a stabilizer for organic materials subject to oxidative and/or thermal degradation, a combination consisting essentially of (1) a hydroxyphenylalkyleneyl isoCyanurate of the formula
 2. A combination of claim 1 where in (1) R'''' and R'''''' are equal to R'', r1 is a tertiary alkyl radical containing 4 to about 12 carbon atoms, r2 is an alkyl radical containing 1 to about 12 carbon atoms, r3 and r4 are hydrogen, and m
 1. 3. A combination of claim 2 where (1) has the formula
 4. A combination of claim 3 where in (2), n 0, and R is an alkylene radical of 1 to about 10 carbon atoms or an alkoxyalkyl radical containing 2 to about 10 carbon atoms.
 5. A combination of claim 4 consisting of 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate and tetrakis(dodecylthio)-1,6-dithiohexylene diphosphite.
 6. A COMPOSITION (A) AN ORANGANIC MATERIAL SUBJECT TO OXIDATIVE AND/OR THERMAL DEGRADATION, AND (B) AS THE ONLY STABILIZER, A COMBINATION OF (1 A HYDROXYPHENYLALKYLENEYL ISOCYANURATE OF THE FORMULA
 7. A composition of claim 6 wherein (A) is a poly Alpha -monoolefin polymer, and in (B) (1), R'''' and R'''''' are the same as R'', r1 is a tertiary alkyl radical containing 4 to about 12 carbon atoms, r2 is an alkyl radical containing 1 to about 12 carbon atoms, r3 and r4 are hydrogen, and m
 1. 8. A composition of claim 7 wherein (A) is a poly Alpha -monoolefin homopolymer and in (B) (2), n 0, and R is an alkylene radical of 1 to about 10 carbon atoms or an alkoxyalkyl radical containing 2 to about 10 carbon atoms.
 9. A composition of claim 8 wherein (A) is polypropylene.
 10. A composition of claim 9 wherein B consists of 1,3,5-tris(3, 5-di-t-butyl-4-hydroxybenzyl)isocyanurate and tetrakis(dodecylthio)-1,6-dithiohexylene diphosphite. 